Placed in the frames, they were held in position in the rabbets by laths nailed to the sides so as to prevent any play. The frames were raised to different heights and allowed to fall in such a manner as to cause as much vibration as possible.
1º Ordinary glass was broken with a fall of about 2 feet (0·60 m.).
2º Toughened glass resisted falls from heights of 3 feet 3 inches (1 mètre), 6 feet 6 inches (2 mètres), 8 feet (2·50 m.), 9 feet 9 inches (3 mètres), and 14 feet 6 inches (4·50 m.). It was only broken by a fall of 19 feet 6 inches (6 mètres).
Rectangular plates 6 inches (0·158 m.) by 4¾ inches (0·120 m.) and 1/5 inch (0·006 m.) thick.
These plates were placed in the frame on the ground, as has been previously explained. Known weights falling from known heights were made to strike the plates exactly in the centre. The weights consisted of bronze spheres, one weighing 3½ oz. (100 grammes) and another of twice that weight.
1st. Ordinary glass resisted the weight of 3½ oz., falling from heights of 8 inches (0·20 m.), 12 inches (0·30 m.), 16 inches (0·40 m.), but was broken by a fall of 20 inches (0·50 m.).
2nd. Toughened glass resisted the blow of the 3½ oz. weight falling from heights of 20 inches (0·50 m.), 40 inches (1 mètre), 60 inches (1·50 m.), and 6 feet 6 inches (2 mètres). The 7 oz. weight (200 grammes) being substituted, the plate was broken by it, falling from a height of 60 inches (1·50 m.).
Rectangular plates, 6 inches (0·158 m.) by 4¾ inches (0·120 m.) and 1/6 inch (0·004 m.) thick.
The same conditions were maintained as in the previous trial.
1st. Ordinary glass. The 3½ oz. weight was allowed to fall from heights of 1 foot (0·30), and 16 inches (0·40 m). It was broken by the second blow.